import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;

public class MapTest {
    public static void t1(){
        Map map = new LinkedHashMap();
        map.put("眼子","王焕");
        map.put("张杰","逆战");
        map.put("罗翔","张三");
        map.put("罗翔","张三");
        System.out.println(map);
    }

    public static void t2(){
        Map map = new LinkedHashMap();
        map.put(null,null);
        System.out.println(map);
    }
    public static void main(String[] args) {
        t2();
    }


}
